The chapter Smart Charts focuses on collecting and handling data through measurement, and representation of the collected data. It helps the students to learn how to measure data and collect it for further use. It covers the topics: philosophyCollection of Data philosophyRepresentation of the Collected Data philosophyVarious methods of representating Data NCERT Math-Magic questions are answered in a simple and engaging manner. We have also related 'Learning Concepts and interactive worksheets with the solutions. Our 'Learning Beyond' segment caters to all the probable questions that a child might think out of curiosity. Download Chapter 12 Smart Charts in PDF format for free here.

Download the NCERT Solutions for Smart Charts in PDF

Question 1 :

Yamini did a project ‘Animals and Birds’. She asked each child of her class about one favourite pet animal. She used tally marks to record each answer. For example if someone said ‘cat’ she put one line | in front of ‘cats’. When someone said ‘cat’ again, she added a line. So means two cats and means 5 cats. In all 24 children said ‘cat’ was their favourite animal. Help Yamini complete the table.

a) Look at the tally marks and write the number for each animal in the table. How many children in all did Yamini talk to?

b) Which is the most favourite pet animal in this table?

c) Which pet will you like to have? What will you name it? Which other animals can be kept at home? Discuss.

Answer :

** **a) The correct answer is:

Add the ‘number’ column to find the total number of children she talked to.

24 + 32 + 10 + 22 + 8 + 20 + 15 = 131

b) Do it by yourself. Answers may vary.

c) Do it by yourself. Answers may vary.

Question 2 :

Sumita stood on the road for half an hour and counted the number of vehicles passing by. She made a tally mark for each vehicle. This helped her in counting quickly the total number of vehicles in each group.

a) Write the number of each vehicle in the table.

b) How many vehicles in all did Sumita see on the road in half an hour?

c) Auto rickshaws are thrice the number of trucks — true/false?

d) Make tally marks for 7 more buses and 2 more trucks.

Answer :

The correct answer is:

b) Add the ‘number’ column to find the total number of vehicles seen in half an hour.

28 + 12 + 18 + 15 + 24 + 6 = 103

c) From the given chart:

Number of trucks = 6

Number of auto rickshaw = 6 × 3 = 18

Therefore, the number of auto rickshaws is three times the number of trucks.

Hence, the given statement is true.

d) Tally marks for 7 more buses is:

Tally marks for 2 more trucks is:

Question 3 :

In the EVS period, the teacher asked children whether they help their parents at home. There were different answers. Children named the work in which they help their parents the most. The teacher collected their answers and made a table.

Help most in house work | Number of children |
---|---|

Going to the market | 47 |

Washing utensils | 15 |

Washing clothes | 3 |

Making, serving food | 25 |

Cleaning the house | 10 |

Total children who said they help their parents |

Now you can fill the chapati chart to show the numbers given in the table.

Look and find out: Children who help in making or serving food are

a) One-third of the total children

b) Half of the total children

c) One-fourth of the total children

Answer :

From the given table, the total number of children is

47 + 15 + 3 + 25 + 10 = 100

The correct chapatti chart is shown below.

Based on the chapati chart, the number of children who help in making and serving food is one-fourth of the chart.

Therefore, the correct answer is the option c).

Question 4 :

Find out from the bar chart:

a) Which city is the hottest on 1 June?

b) Which city is the coldest on 1 December?

c) Which city shows little change in temperature on the two days — 1 June and 1 December.

Answer :

a) Observe the given bar chart. The highest temperature on 1st June is 38oC, that is for Jaisalmer. Therefore, Jaisalmer is the hottest city on 1st June.

b) Observe the given bar chart. The lowest temperature on 1st December is 10oC, that is for Shimla. Therefore, Shimla is the coldest city on 1st December.

c) Bangalore shows little change in temperature on the two days.

28 – 24 = 4oC

Question 5 :

Earlier there were no rabbits in Australia. Rabbits were brought to Australia around the year 1780. At that time there were no animals in Australia which ate rabbits. So the rabbits began to multiply at a very fast rate. Imagine what they did to the crops! The table shows how rabbits grew every year.

1) After each year the number of rabbits was —

a) A little less than double the number of rabbits in the last year.

b) Double the number in the last year.

c) 8 more than the number in the last year.

d) More than double the number of rabbits in the last year.

2) At the end of year 6, the number of rabbits was close to

a) 400 b) 600 c) 800

3) After which year did the number of rabbits cross 1000?

Answer :

1) Observe the given table, after each year the numbers are a little less than double the numbers in the last year. Therefore, the correct answer is option a).

2) The number of rabbits is increasing a little less than double every year. Therefore, at the end of year 5 it will be close to 200, and at the end of year 6 it will be close to 400.

Hence, the correct answer is option a).

3) The number of rabbits is increasing a little less than double every year. Therefore, at the end of year 5 it will be about 200, at the end of year 6 it will be about 400, at the end of year 7 it will be about 800, and at the end of year 8 it will be about 1600.

Since it was started in the year 1780, after the year 1788 it crossed 1000.

Question 6 :

Madhav went to a wedding along with his parents. He met many relatives there. But he didn’t know everyone. He met his mother’s grandfather, but found that her grandmother is not alive. He also found that her mother (grandmother’s mother) is still alive, and is more than a hundred years old.

Madhav got confused. He couldn’t imagine his mother’s grandmother’s mother! So, Madhav’s mother made a family tree for him —

Madhav’s mother helped him understand her family with the help of this drawing. You can also find out about your older generations using such a family tree.

Answer these questions:

a) How many grandparents in all does Shobna have?

b) How many great – great- grandparents in all does Madhav have?

c) How many elders will be in the VII generation of his family?

d) If he takes his family tree forward in which generation will he find 128 elders?

Answer :

a) Shobna has four grandparents.

b) Madhav has eight great-great-grandparents in all.

c) 32 elders will be in the VII generation of his family.

d) Number of members in VII generation = 32

Number of members in VIII generation = 32 × 2 = 64

Number of members in IX generation = 64 × 2 = 128

So, in the IX generation, the number will be 128.

Question 7 :

Amit sowed a few seeds of moong dal in the ground. The height of the plant grew to 1.4 cm in the first four days. After that it started growing faster.

Amit measured the height of the plant after every four days and put a dot on the chart. For example if you look at the dot marked on the fourth day, you can see on the left side scale that it is 1.4 cm high.

Now look at the height of each dot in cm and check from the table if he has marked the dots correctly.

Find out from the growth chart: a) Between which days did the length of the plant change the most?

i) 0-4 ii) 4-8 iii) 8-12 iv) 12-16 v) 16-20

b) What could be the length of this plant on the 14th day? Guess.

i) 8.7 cm ii) 9.9 cm iii) 10.2 cm iv) 10.5 cm

c) Will the plant keep growing all the time? What will be its length on the 100th day? Make a guess!

Answer :

The dots are marked correctly.

a) Observe the given chart.

Increase in the length of the plant between 8–12 days

= 9.5 cm − 5.3 cm

= 4.2 cm

Which is the maximum. Hence the correct answer is option iii).

b) The length of the plant on the 12th day = 9.5 cm

The length of the plant on the 16th day = 10.2 cm

So, the possible length of the plant on the 14th day must lie between 9.5 cm and 10.2 cm.

Therefore, the correct answer is option ii).

c) Do it by yourself. Answers may vary.

Question 8 :

Ask 10 of your friends about what they like to do most after school.

What they like to do after school | Number of children |
---|---|

Watching TV | |

Playing football | |

Reading story books | |

Answer :

Do it by yourself. Answers may vary. A sample answer is:

What they like to do after school | Number of children |
---|---|

Watching TV | 2 |

Playing football | 3 |

Reading story books | 1 |

Listening music | 1 |

Sleeping | 1 |

Drawing | 2 |

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